Pendulums are quite safe to use, they are not the same as Ouija boards. I've been using a pendulum for over thirty years with no problems at all.
The muscle twitches that move the pendulum are caused by signals that are sent along the neurological pathways. These signals are sent through the subconscious.
Can I ask why you buried it?
The dream you had sounds more like you astrally projected in your dream (many people experience hearing the wind when they project).
The only thing that may have happened is the pendulum helped open your intuitive and psychic chanels.
Jenny Crow